3 Axis Fanuc controller Loosing home when powered off?

[FanucIssues]

This is a stupid question, but we have been stumped.

For some time now, if we are to power our machine off, we will loose x, y, and z home position. It is a Murata Dual spindle with a gantry system, it runs off of a Fanuc 18i-T controller, and the servo drive for the gantry is a Fanuc A06B-6096-H303. We have swapped the servo amp, power supply, battries, and I don't even remember what else. I know it is getting good power from the power supply, both on the bus line, and within the 24 volt circuit. But I wonder about the encoder cables, could that be where there is a short, and not letting the system charge the battries, as well as holding a charge?

But, at a loss here....And would love to have any help.

[Al_The_Man]

I assume there is a common battery for the three encoders?
Did you monitor the battery voltage at switch off, and again before switching on after the machine has been off for a while, this should tell you if the batteries are being charged or holding one.
Al.

[FanucIssues]

I have not. That is a good idea though, and with that, to seperate the encoder cables one at a time...That should isolate which one there could be an issue with if the battery voltage is good before dropping power. Have you done this before?


Thanks for the little nudge. I don't have many experianced people at work to bounce ideas off of. But, I will run with that, and see what I can come up with. It will be a while though, that machine is one of our bread winners, and it's running at the moment. It will have to be a sunday project for next week. I'll let you know.

[bborb]

Fanucs don't "re-charge" batteries. Rechargeable batteries is a no-no in a Fanuc. There is no built in battery charger in a Fanuc. You should get a low battery alarm if that problem exists.
I had a battery problem and lost reference position. After changing batteries we had to change parameters 1002, 1005, and 1815 to "re-home" the machine, then go and change the parameters back. If you forget to change them back you will experience the dilemma described above.
HTH

[FanucIssues]

After changing batteries we had to change parameters 1002, 1005,
HTH

I didn't know about those two, I also didn't relize that they don't charge, guess it would make sence...only having two wires. I can auto home it, and I'll watch the APZ make sure it changes, then the next, and the last.



I'll look em up when I return to work (tuesday).

[FanucIssues]

After changing batteries we had to change parameters 1002, 1005, and 1815 to "re-home" the machine,
HTH

I've looked at the parameters, and I am a wondering what bit(s) to change, I'm assuming it would be the DLZ, or #1 bit, but I just wanted to make sure.

[bborb]

Yeh, our machine had (slow down) dogs, otherwise you'd have to jog within one revolution of home before referencing.

[bborb]

Hey, did you get that problem solved?

[FanucIssues]

I haven't had a chance to play with it yet, production has been running it, we'll get around 1500 to 1800 pcs a day, and we need to run it. I did shut it down today I found out that someone had jumpered the prox switches for the door closed, so yeh, my lock went on it quicker then you can say stop running it. I did swap battries, and the problem followed the dead battries...go figure. But I have a feeling there is a short in one of the wires, if it was to be left off for a while, I'm sure we would have two dead six volt battries.

[dpuch]

What, you turn it off?

Sorry, now to be serious.
Our 16i controls have a battery on the drives, and there is also a capacitor in the servo encoder. The battery is a lithium (non rechargable) and it powers the cap in the encoder so it can keep track of position when the power is off. The cap alone will even let it track position for a while (30 min or so) with the encoder cable unpluged. The battery should only be draining when the drive power is off, and you should get warnings about low batteries, followed by the dead battery error, depending on how fast it drains and how long it was off.

You can find the batteries online for cheaper than thru fanuc, do a few google searches.

Dale

[FanucIssues]

Your right lithium 6 volt, I think he had found them for forty bucks or something, I'm not sure hat they are from Fanuc, or even our drive repair company.